Liquid fuel is most commonly used with internal combustion engines, and is likely to continue so because of the ease of handling, storage and the like. The use of liquid fuels requires that some means be provided for intimately admixing the liquid, in a finely divided state, with air to be placed into a cylinder of an engine for combustion.
Conventionally, carburetors have been used to provide the desired mixture of fuel and air, the conventional carburetor comprising, in general, means for spraying liquid fuel into a draft of air, and means for creating sufficient turbulence to cause the desired mixing of the atomized fuel with the air. Such an arrangement is difficult to control since liquid fuel is simply sprayed into a moving column of air, and the amount of the liquid to be sprayed at any given instant needs to be controlled in accordance with a large number of variables. The conventional carburetor therefore becomes increasingly complex as the liquid flow is made dependent on an increasing number of different conditions. Also, it will be recognized that, even though the liquid is sprayed in a fine mist, it is still a substantial liquid that is placed into the intake manifold, then into the cylinder of the combustion engine. There have been some efforts at providing means for vaporizing the liquid prior to placing the fuel into the cylinder, but these devices have been unduly complex, and have frequently been used in conjunction with a substantially conventional carburetor in an effort to obtain the required control over the internal combustion engine.